// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/thread_task_runner_handle.h"

#include "base/lazy_instance.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/thread_local.h"

namespace base {

namespace {

    base::LazyInstance<base::ThreadLocalPointer<ThreadTaskRunnerHandle>>::Leaky
        lazy_tls_ptr
        = LAZY_INSTANCE_INITIALIZER;

} // namespace

// static
scoped_refptr<SingleThreadTaskRunner> ThreadTaskRunnerHandle::Get()
{
    ThreadTaskRunnerHandle* current = lazy_tls_ptr.Pointer()->Get();
    DCHECK(current);
    return current->task_runner_;
}

// static
bool ThreadTaskRunnerHandle::IsSet()
{
    return lazy_tls_ptr.Pointer()->Get() != NULL;
}

ThreadTaskRunnerHandle::ThreadTaskRunnerHandle(
    scoped_refptr<SingleThreadTaskRunner> task_runner)
    : task_runner_(task_runner)
{
    DCHECK(task_runner_->BelongsToCurrentThread());
    DCHECK(!lazy_tls_ptr.Pointer()->Get());
    lazy_tls_ptr.Pointer()->Set(this);
}

ThreadTaskRunnerHandle::~ThreadTaskRunnerHandle()
{
    DCHECK(task_runner_->BelongsToCurrentThread());
    DCHECK_EQ(lazy_tls_ptr.Pointer()->Get(), this);
    lazy_tls_ptr.Pointer()->Set(NULL);
}

} // namespace base
